Specimens of Tyrannosaurus

Tyrannosaurus rex, one of the most iconic dinosaurs, is known from numerous specimens, some of which have acquired a degree of notability in their own right because of their scientific importance and coverage by the media. See Tyrannosaurus for more information on the genus itself.

The holotype of Tyrannosaurus rex, a partial skull and skeleton originally called AMNH 973 (AMNH stands for American Museum of Natural History), was discovered in the U.S. state of Montana in 1902 and excavated over the next three years. Another specimen (AMNH 5866), found in Wyoming in 1900, was described in the same paper under the name Dynamosaurus imperiosus. At the time of their initial description and naming, these specimens had not been fully prepared and the type specimen of T. rex had not even been fully recovered.[1] In 1906, after further preparation and examination, Henry Fairfield Osborn recognized both skeletons as belonging to the same species. Because the name Tyrannosaurus rex had appeared just one page earlier than Dynamosaurus in Osborn's 1905 work, it was considered the older name and has been used since. Had it not been for page order, Dynamosaurus would have become the official name.[2]

The first named fossil specimen which can be attributed to Tyrannosaurus rex consists of two partial vertebrae (one of which has been lost) found by Edward Drinker Cope in 1892. Cope believed that they belonged to an "agathaumid" (ceratopsid) dinosaur, and named them Manospondylus gigas, meaning "giant porous vertebra" in reverence to the numerous openings for blood vessels he found in the bone.[3] The M. gigas remains were later identified as those of a theropod rather than a ceratopsid, and H.F. Osborn recognized the similarity between M. gigas and Tyrannosaurus rex as early as 1917. However, due to the fragmentary nature of the Manospondylus vertebrae, Osborn did not synonymize the two genera.[4]

CM 9380 is the type specimen used to describe Tyrannosaurus rex. Fragments of (then) AMNH 973 were first found in 1902 by Barnum Brown, assistant curator of the American Museum of Natural History and a famous paleontologist in his own right. He forwarded news of it to Osborn; it would be three years before they found the rest of it. It has been reconstructed in recent years, it measured 11.9 meters and has an estimated weight of around 7.3 metric tons, although most other studies have suggested lower weight figures.[5] In 1905 when the type was described by Osborn, previous knowledge of dinosaur predators at the time were based on Jurassiccarnosaurs, so the short fore-arms of the Tyrannosaurus were treated with extreme caution, with suspicion that bones of a smaller theropod had become jumbled with the remains of the bigger fossil.[1][6] Following the 1941 entry of the United States into World War II, the holotype was sold to the Carnegie Museum of Natural History in Pittsburgh for protection against possible bombing raids.[7] The specimen, now labeled CM 9380, is still mounted in Pittsburgh, at first with the tail acting as a tripod in the old fashioned kangaroo pose. It has since received a modernization of its posture and can now be found balancing with tail outstretched.

AMNH 5027 was discovered and excavated in 1908 by Barnum Brown in Montana, and described by Osborn in 1912 and 1916. At the time of discovery, a complete cervical (neck vertebrae) series for Tyrannosaurus was not previously known, so it was this specimen that brought the short, stocky tyrannosaur neck to light. Compared to later specimens (BMNH R7994 and FMNH PR2081, for instance) the cervical series of AMNH 5027 is much more gracile, so with later discoveries the distinction between tyrannosaurid necks and the necks of carnosaurs became more obvious.[8] This specimen also provided the first complete skull of Tyrannosaurus rex. In total, Brown found five partial Tyrannosaurus skeletons.

Osborn planned to mount the similarly-sized AMNH 5027 and AMNH 973 together in dynamic poses.[9] Designed by E.S. Christman, the scene was to depict a rearing Tyrannosaurus (AMNH 5027) snapping at another cowering one (AMNH 973), as they fought over the remains of a hadrosaur, described at the time as Trachodon:

"It is early morning along the shore of a Cretaceous lake four [we now know to be sixty five] million years ago. A herbivorous dinosaur Trachodon venturing from the water for a breakfast of succulent vegetation has been caught and partly devoured by a giant flesh eating Tyrannosaurus. As this monster crouches over the carcass, busy dismembering it, another Tyrannosaurus is attracted to the scene. Approaching, it rises nearly to its full height to grapple the more fortunate hunter and dispute the prey. The crouching figure reluctantly stops eating and accepts the challenge, partly rising to spring on its adversary. The psychological moment of tense inertia before the combat was chosen to best show positions of the limbs and bodies, as well as to picture an incident in the life history of these giant reptiles."[6]

Scale model of the never-completed Tyrannosaurus rex exhibit planned for the American Museum of Natural History by H.F. Osborn; AMNH 973 is the cowering individual, and AMNH 5027 is the other individual.

However, technical difficulties prevented the mount from being executed. One obvious problem was that the Cretaceous Dinosaur Hall was too small to accommodate this dramatic display, and AMNH 5027 was already mounted by itself as the central attraction of the hall. The fore-arms of Tyrannosaurus were not well documented and the hands were unknown, so for the sake of the display, the forearms of AMNH 5027 were given three fingers, based on the forelimbs of Allosaurus (the more allosaur-like arms were replaced several years later when better fossils of tyrannosaurid arms were found). The mount retained a rearing pose similar to the initial proposal. By the 1980s it was generally accepted that such a pose would have been anatomically impossible in life, and the skeleton was re-mounted in a more accurate, horizontal pose during a renovation of the museum's dinosaur halls in the early 1990s. The mount can still be seen on display on the fourth floor of the American Museum.

After the war, the holotype of Dynamosaurus imperiosus and a second specimen (AMNH 5881) were also sold and now reside in the collections of the Natural History Museum, London (formerly the British Museum of Natural History), where they are known as BMNH R7994 and BMNH R7995, respectively. The American Museum of Natural History features AMNH 5027 in its famed Hall of Saurischian Dinosaurs to this day.

Very few other Tyrannosaurus rex skeletons were discovered until the late 1980s. The skull of Nanotyrannus, frequently considered to be a juvenile T. rex, was recovered from Montana in 1942. In 1966, a crew working for the Natural History Museum of Los Angeles County under the direction of Harley Garbani discovered another T. rex (LACM 23844) which included most of the skull of a very large, mature animal. When it was put on display in Los Angeles, LACM 23844 was the largest T. rex skull on exhibit anywhere. Garbani also discovered several other partial skeletons over the next decade (including LACM 23845, the holotype of "Albertosaurus" megagracilis), some of which are maintained in the collections of the University of California Museum of Paleontology in Berkeley, California. Other skulls and partial skeletons were discovered in South Dakota and Alberta, Canada in the early 1980s.[10]

Before 1987, Tyrannosaurus rex was thought to be rare.[10] However, the last two decades have seen the discovery and description of over a dozen additional specimens. The first, nicknamed "Stan" in honor of its discoverer, amateur paleontologist Stan Sacrison, was found in the Hell Creek Formation near Buffalo, South Dakota, in the spring of 1987. After 30,000 hours of digging and preparation by the Black Hills Institute, beginning in 1992, 65% of a skeleton emerged, including a complete skull. Stan (BHI 3033) is currently on display in the Black Hills Museum of Natural History in Hill City, South Dakota following an extensive world tour, and replicas sold by the Black Hills Institute are also found in museum exhibit halls around the world. This specimen exhibits many bone pathologies, including broken and healed ribs, a broken and healed neck and a spectacular hole in the back of its head, about the size of a Tyrannosaurus tooth.[11]

Black Beauty (specimen number RTMP 81.6.1) is a well preserved fossil of Tyrannosaurus rex. The nickname stems from the apparent shiny dark color of the fossil bones, which occurred during fossilisation by the presence of minerals in the surrounding rock. The specimen is housed in the Royal Tyrrell Museum in Drumheller, Alberta, Canada.[12] Black Beauty is the 14th of the 20 most complete skeletons of Tyrannosaurus rex found so far,[13] and casts are on display in museums around the world. In 2009, a paper by Jack Horner and colleagues illustrated the concept of parasitic infections in dinosaurs by analysing the lesions found on the cranial bones of Black Beauty.[14] The specimen has been used to study comparative morphology between tyrannosaurids and Tyrannosaurus individuals, and some[who?] have suggested that Black Beauty should be classed as Dynamosaurus (=Tyrannosaurus).[15] Black Beauty is considered to be the smallest of all known adult T. rex specimens.[16]

Black Beauty was found in 1980 by Jeff Baker, while on a fishing trip with a friend in the region of the Crowsnest Pass, Alberta. A large bone was found in the riverbank and shown to their teacher. Soon afterward, the Royall Tyrrell Museum was contacted,[17] and excavation of the sandstone matrix surrounding the fossils began in 1982.[18]

Replicas of Black Beauty have been shown in some exhibitions and museums, including both simple skull montages and complete skeletons. The Naturhistoriska riksmuseet in Stockholm has a mounted complete skeleton of Black Beauty as one of their primary exhibitions called 4 ½ miljarder år, featuring the history of earth and life.[19] Black Beauty has also been displayed in Paleozoological Museum,[20] and a replica of the skull is on display at the Museum of African Culture.[21] It was also part of the traveling exhibit Dinosaur World Tour in the 1990s[22]

It is estimated that the "Wankel rex" was 18 years old when it died, an adult but not completely grown. It is also one of the largest T. rex specimens ever found. The "Wankel rex" was also one of the first fossil dinosaur skeletons studied to see if biological molecules still existed within the fossilized bones. Doctoral candidate Mary Schweitzer found heme, a biological form of iron that makes up hemoglobin (the red pigment in blood).[24]

The Corps of Engineers owns the "Wankel rex", and for years permitted its display at the Museum of the Rockies. In June 2013, the Corps loaned the specimen to the National Museum of Natural History, Smithsonian Institution museum in Washington, D.C., for 50 years. The specimen will go on temporary display on National Fossil Day, October 16, 2013, and will be exhibited until the museum's dinosaur hall exhibit closes for renovation in the spring of 2014. The skeleton will be the centerpiece of the dinosaur hall when it reopens in 2019.[25] (The Museum of the Rockies has about a dozen T. Rex skeletons, and will mount an 80 percent-complete specimen once the "Wankel rex" has been shipped to the Smithsonian.)[24]

Susan Hendrickson of the Black Hills Institute discovered the best-preserved Tyrannosaurus currently known, in the Hell Creek Formation near Faith, South Dakota, on 12 August 1990. This specimen, named "Sue" in honor of its discoverer, soon became embroiled in a legal battle over its ownership. The land on which the fossil was discovered was found to lie within the Cheyenne River Indian Reservation and is occupied by the family of Maurice Williams, a Native American of the Siouxtribe. In 1992, Williams claimed he still owned the fossil, for which the Black Hills Institute had paid him USD 5,000. The local Cheyenne River Sioux Tribe, of which Williams is a member, also claimed ownership. The fossil, as well as many thousands of pages of field notes and business records, were confiscated by the Federal Bureau of Investigation in 1992 and held throughout the ensuing court proceedings. In 1997, the suit was settled in favor of Maurice Williams because his land is technically held in trust for him by the United States government. Therefore, although the Black Hills Institute had paid Williams for the fossil, it was judged that the fossil could be considered "land" which Williams owned but could not legally sell without government permission. The fossil was returned to Williams' ownership and Pete Larson, vice-president of the Black Hills Institute, was sentenced to two years in federal prison for an unrelated customs violation discovered by the FBI while searching through his business records. Williams quickly offered up "Sue" for auction by Sotheby's in New York, where it was sold to the Field Museum of Natural History in Chicago for USD 8.4 million – the highest price ever paid for a fossil. Preparation of "Sue" (FMNH PR2081) was completed at the Field Museum and her skeleton was placed on exhibit on 17 May 2000.[26][27] Over 90% of the skeleton was recovered, allowing the first complete description of a Tyrannosaurus rex skeleton.[28] It has an estimated length of 12.3 meters and a weight estimated at 6.1 to 9.5 tonnes.[5][29]

Like many other fossils of Tyrannosaurus rex, the skeleton of Stan shows many broken and healed bones. These include broken ribs and damages in the skull. One of the most prominent injuries are in the neck and the skull. A piece of bone is missing at the rear, and the skull also bears a hole 1 inch wide, probably made by another Tyrannosaurus. Also, two of the cervical vertebrae are fused, and another has additional bone growth. This could have been caused by another Tyrannosaurus bite. The bite marks are healed, indicating that Stan survived the wounds.[38] Stan could also have been infected by Trichomonas-like parasites.[39]

Peck's Rex (also known as "Peckrex", "Rigby's rex" and Tyrannosaurus "imperator"[40]) is the nickname (specimen number MOR 980) given to a fossil specimen found in Montana in 1997.[41] The discovery was made by Louis E. Tremblay on July 4, 1997 working under the supervision of J. Keith Rigby Jr. who led the excavation and bone preparation.

The fossil got its nickname after Fort Peck, which is located close to the place of discovery. Peck's Rex has been part of several exhibitions on dinosaurs, and is specifically famous because it was the first specimen of its species to have Metacarpal III preserved.[42][43]

The fossil of Peck's Rex is relatively well preserved.[44] The skeleton includes a relatively complete skull with jaws, multiple vertebrae of the back and tail, a well preserved gastralium, and hipbone with complete ischium and pubis. The left hindleg is relatively complete, missing only some toe bones. The forelimbs include the scapula and furcula, both humeri and right hand phalanges, as well as metacarpal III. Because the skeleton is of the gracile morphotype, Peck's Rex is believed to be a male, although the hypothesis which suggests that the sex of Tyrannosaurus specimens can be determined by the degree of skeletal sturdiness has been debated in recent years. Peck's Rex has been the subject of research regarding parasitic infections in dinosaurs.[45] The forelimbs of Peck's Rex have also been studied as they show evidence of use. This evidence includes the construction of metacarpal III, as well as repeated fractures in the furcula - possibly caused by heavy loads or pressure (Carpenter and Lipkin, 2005).[46]

Bucky is a fossil of a juvenile specimen located in the Dinosphere exhibit in The Children's Museum of Indianapolis in Indianapolis, Indiana, United States. Some paleontologists suggest that female T. rex were of the robust morphotype, which includes Bucky, but this method for distinguishing gender is not universally accepted.[53] It is the first juvenile Tyrannosaurus ever placed on permanent exhibit in a museum and was the first to be identified with a furcula.[54]

Bucky has a bird-like skeletal structure, as it is one of the few dinosaur fossils found with a furcula.[55] A furcula, or fused clavicles, is a boomerang shaped "wishbone" that would measure 29 centimetres (11 in) wide and 14 centimetres (5.5 in) high. Bucky's furcula is the first one found for the genus Tyrannosaurus.[56] The furcula is thought to be a link between dinosaurs and birds and is the center of debate surrounding the origin of birds. Bucky also has a nearly complete set of gastralia, or belly ribs, and an ulna, or lower arm bone. As of now, 101 bones, or about 34% of Bucky's skeleton, has been discovered and verified.[57] Bucky is the sixth most complete Tyrannosaurus rex out of more than 40 that have been discovered.[54] Bucky's tail is the third most complete tail of any Tyrannosaurus rex known and has a nearly complete vertebral column to the end of the pelvis. Bucky's skull is a reconstruction which utilized modified casts of other Tyrannosaurus rex specimens.[58]

Cast of the "Bucky" specimen

Bucky is displayed in the Children's Museum of Indianapolis. Found in Dinosphere, Bucky is displayed along with Stan, an adult Tyrannosaurus, in a hunting scene. Both dinosaurs are attacking Kelsey the Triceratops. Bucky attacks Kelsey from behind, while Stan acts as a diversion in front of the triceratops. The end of the fight is left ambiguous. Bucky is displayed with a full set of gastralia, which is unusual. But because Bucky was discovered with a full set, it is displayed along with it.[59]

The dinosaur remains were found in 1998 in the Hell Creek Formation near the town of Faith, South Dakota. The skeleton, transported by water, ended up in a low shallow valley along with bones from an Edmontosaurus and Triceratops. It was discovered by rancher and cowboy Bucky Derflinger. The excavation site was 150 by 30 feet (45.7 m × 9.1 m), about 4,500 square feet (420 m2).[57] Bucky was well preserved and easily prepared by the Black Hills Institute in South Dakota. Excavation and preparation of Bucky was relatively easy because the surrounding rock matrix was soft.[60]

Bucky Derflinger found Bucky's skeleton in 1998 when he was 20 years old. He was a rancher and a rodeo cowboy. While breaking in a young horse on his father's ranch, Derflinger discovered a pes phalange, or toe bone, from Bucky's skeleton. He has also discovered another Tyrannosaurus and a slew of remains of duck-billed dinosaurs on his father's land. Derflinger is the youngest person to discover a Tyrannosaurus. He has been collecting dinosaur fossils since he was eight years old.[61]

After four years of preparation, Jane was put on display at Rockford, Illinois' Burpee Museum of Natural History as the centerpiece of an exhibit called "Jane: Diary of a Dinosaur." Paleontologists who support the theory that Jane represents a juvenile believe the tyrannosaur was approximately 11 years old at its time of death, and its fully restored skeleton measured 6.5 metres (21.3 ft) long, a bit more than half as long as the largest known complete T. rex specimen, nicknamed "Sue," which measures 12.3 m (40.3 ft) long. The weight of the Jane specimen in life was probably nearly 680 kg (1,500 lbs). Its large feet and long legs indicate it was built for speed and could possibly run as fast as 20–30 miles per hour. Its lower jaw has 17 curved, serrated teeth.

Despite having a typically female name, Jane's sex is unknown—the specimen was named after Burpee Museum benefactor Jane Solem. The specimen was found in the summer of 2001 by Carol Tuck and Bill Harrison on an expedition led by Burpee Museum curator Michael Henderson.[63]

The Jane specimen has been central to the debate regarding the validity of the proposed tyrannosaurid genus Nanotyrannus. Jane's skull is nearly identical to the skull of the original Nanotyrannus specimen, confirming that they belong to the same species. A conference was held at the Burpee museum in 2005, during which paleontologists debated whether these "pygmy tyrants" represented adult specimens of a small species, or juvenile specimens of Tyrannosaurus rex. While there were a few dissenters,[64] a majority of paleontologists at the conference decided on the latter, and that both Jane and Nanotyrannus were juvenile T. rex.[65][66] However, the Jane material has yet to be properly studied and described by scientists. This research is currently being undertaken by Robert T. Bakker, Peter Larson, and Phil Currie, and should help settle the question once it is officially published.[67]

Femur of MOR 1125 from which demineralized matrix and peptides (insets) were obtained

In the March 2005 Science magazine, Mary Higby Schweitzer of North Carolina State University and colleagues announced the recovery of soft tissue from the marrow cavity of a fossilized leg bone, from a 68 million-year-old Tyrannosaurus. The bone had been intentionally, though reluctantly, broken for shipping and then not preserved in the normal manner, specifically because Schweitzer was hoping to test it for soft tissue. Designated MOR 1125 (and known informally as B-rex), the dinosaur had been excavated from the Hell Creek Formation. Flexible, bifurcating blood vessels and fibrous but elastic bone matrix tissue were recognized. In addition, microstructures resembling blood cells were found inside the matrix and vessels. The structures bear resemblance to ostrich blood cells and vessels. However, since an unknown process distinct from normal fossilization seems to have preserved the material, the researchers are being careful not to claim that it is original material from the dinosaur.[68] If it is found to be original material, any surviving proteins may be used as a means of indirectly guessing some of the DNA content of the dinosaurs involved, because each protein is typically created by a specific gene. The absence of previous finds may merely be the result of assumptions that soft tissue could not be preserved, so that nobody had looked for it. Since the first, two more tyrannosaurs and a hadrosaur have also been found to have such tissue-like structures.[69][70]

Paleontologist Thomas Kaye of the University of Washington in Seattle has also hypothesized that the soft-tissue is permineralized biofilm created by bacteria while digesting and breaking down the original specimen. He has discovered this to be true in many specimens from the same area.[71]

Following the sale of "Sue," another Tyrannosaurus rex skeleton was, under the individual name of "Z-rex", put up for auction on eBay in 2000 with an asking price of over USD 8 million. It failed to sell online but was purchased for an undisclosed price in 2001 by British millionaire Graham Ferguson Lacey, who renamed the skeleton "Samson" after the Biblicalfigure of the same name. This specimen, discovered on private land in Harding County, South Dakota on October 4, 1992 by Brian Williams, Michael Zimmerschied, and Dee Zimmerschied (Alan and Robert Detrich were the ones who helped excavate the skeleton) includes a complete and undistorted skull, which was prepared by the Carnegie Museum starting in May 2004.[72] After preparation was complete in March 2006, the specimen was returned to its owner, who plans to put it on an educational tour.[73] "Samson" along with some other dinosaur skeletons was sold at auction on 3 October 2009, exhibited in early 2011 at the Embedded Systems Conference Silicon Valley.

On August 16, 1991, then high school teacher, Robert Gebhardt joined Royal Saskatchewan Museum palaeontologists on a prospecting expedition to the exposed bedrock along the Frenchman River Valley located in southwestern Saskatchewan, Canada to learn how fossils are found and identified in the field. Within a half a day, he discovered the base of a heavily worn tooth, and a vertebra from the tail, both suggesting that they belonged to a T. rex. In June 1994, RSM palaeontologists lead by Tim Tokaryk (who gave Scotty his name) began excavating the T. rex. Locals say Scotty was named so after Tokraryk bought an expensive bottle of Scotch Whisky to celebrate the discovery. The 66 million year old skeleton was the first T. rex skeleton found in Saskatchewan and one of only 12 known in the world at the time. Scotty is one of the largest and most complete skeletons unearthed measuring an estimated 12 meters in length. A complete articulated cast of the skeleton was finally completed in 2012 and is now on display at its permanent home at the T.rex Discovery Centre located in Eastend, Saskatchewan, Canada near to the location of the discovery.[74]

^Many sources says that "Stan" is the second most complete specimen, except for "Sue" (FMNH PR 2081). Some sources say that "Stan" are complete to about 65% [1], other claim it is complete to about 70% [2].

^Larson (2005). "A case for Nanotyrannus." In "The origin, systematics, and paleobiology of Tyrannosauridae”, a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University.

^Currie, Henderson, Horner and Williams (2005). "On tyrannosaur teeth, tooth positions and the taxonomic status of Nanotyrannus lancensis." In "The origin, systematics, and paleobiology of Tyrannosauridae”, a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University.

^Henderson (2005). "Nano No More: The death of the pygmy tyrant." In "The origin, systematics, and paleobiology of Tyrannosauridae”, a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University.